Process of making styli and products thereof



23,1914. 1,396,41 2. Patented Nov. 8, 1921.

UNTED STATES PATENT OFFICE.

:BYRON E. 'ELDRED, OF NEW YORK, N. Y., ASSIGNOR TO THE COMMERCIAL RESEARCH COMPANY, A CORPORATION 0F NEW YORK.

BOCESS OF MAKING STYLI AND PRODUCTS THEREO. l

Specification of Letters Patent.

Patented Nov. 8, 1921.

Application led December 23, 1914. Serial No. 878,804.

To all who/m. tf/nay concern- Be it known that l, BYRON E. ELDRED, a citizen ot the United States, residing at New York, in the county ot New-York and State ot New York, have invented certain new and useful Improvements in Processes ot Making Styli and Products Ihereot, of which the following is a specification.

rlhis invention relates to processes of making styli and products thereof; and it comprises a method wherein a rod or bar of hard low heat-conductive metal, such as tungsten or tungsten group metal or alloy, ot any desired cross section, is covered with a sheath ot protecting metal, advantageously high heat-conductive stili and strong, highmelting metal, such as iron. steel, nickel, nickel steel, or the like, and the two are c0- worked down to stylus-diameter, cut intostylus lengths and the core of one or both ends of each such length exposed and pointed it desired, and it further comprises a compound stylus having a core ot hard low heat-conductive metal, such as tungsten tungsten group metal or alloy and a sheath ot higher heat-conductive highmelting and strong metal, such as steel, iron, nickel, nickel steel and the like, the core being exposed at one or both ends and pointed it' desired; all as more fully hereinafter forth and as claimed.

lt is a desideratum in the use of talking machines to provide a sound producing stylus which may be used a number of times without production ot' scratchy or discordant sounds. rThe metal styli heretofore known are subject to the disadvantage that they can be used a very few times; one use ordinarily being suihcient to wear the metal down enough to render them useless. To overcome this disadvantage it has been proposed to use styli having inset jewels serving as hard points but these are very expensive and diiiicult to produce. :it has also been proposed to provide Styli with hard metal points,l such as tungsten and the like in much the same way but such compound styli have not been generally adopted because it is practically impossible on the large scale to manufacture them in the size necessary. lt is difficult to drill in the holding element the. minute socket hole which is necessary and it is equally diicult to hold down, the mass is not uniform in texture or physical characteristics throughout, this being due to the diiferential'lieating or cooling of the outside and of the inner layers. The outside is usually of fibrous texture. As a rule, the extremely hard metals and alloys, which serve best for use as phonograph needles, are metals having low heat conductivity. An advantage of my process hereafter more fully explained is that such metals useful for phonograph-needles may be worked to stylus-size without resulting local changes in physical characteristics and without fibrous texture. Aflbrous character is very objectionable in a talking machine needle.

F or this purpose I work down the hard, tough metal inside a sheath of high melting stift and strong metal, best a metal of the iron class. rThe use of a special body of stili' and strong metal as an envelo or sheath serves not only as a heat retaining -member to maintain the core at a workable heat but also acts in `the nature ot a holding ,tool in working the obre to the requisite size.

While tungsten per se is particularly adaptable for talking machine needles under the present invention, I may use other hard metal' or hard metal alloy cores. High speed steels, such as an alloy of iron with l2 to 15 per cent.yot tungsten, are pgrticularly advantageous. Other hard metal alloys may lalso be employed.

Styli comprising a needle point of such a metal as tungsten made in accordance with the present process are capable of use several hundred times. i'

As a typical example of one method of making acompound metal stylus according to my invention, I first produce a bar or rod of tungsten of the desired length and of the required cross section and insert it in a hot tube of a metal of the iron group, such as nickel, steel or nickel-steel, and heat the two to such a temperature that thev unequal expansion of the metals causes a workable Vworked hot, on coolin holding union between the two. The comipound metal article produced is then reduced in cross sectional area by any known means, such asswaging, wire drawing, et,c, until it is of stylus diameter, whereupon it is cui'J into stylus lengths, the sheath turned off' or otherwise removed from one or both ends to expose suflicient length of the tungsten core to travel in the record grooves and, if desired, the exposed ends furtherpointed. rIhe tungsten thus drawn down within the sheath to needle size has a smooth surface, is non-fibrous,` extremely hard and is particularly useful for transmitting the vibration from the 'record of the sound producing machine to the diaphragm to reproduce Sound. u

The two metals hav'i ng been assembled and a shrunk-on fit of the sheath exists which, on the one hand, gives a firm grip of core by sheath, precluding chatteringi in use and also the minor vibrations which are destructive to vthe clearness of tone, and, on the other hand, facilitates the operation of exposing the. point by local removal of the shath. In

-turning ofi' in a. lathe the sheath strips readily, leaving the core without tool marks and of -a smooth, even surface texture due to the working down method. With proper manipulation in cutting, the core and sheath spring apart slightly and the cutting tool rides the core without cutting it. Vith tungsten and tungsten alloys. (some of which are hard enough to scratch sapphire), this 'has the further advantagev of saving wear on the cutting tool.

The surface texture of the exposed core is one which is highly advantageous for the Apresent purposes and one which cannot be produced by working naked tungsten or by abrading tools.

The compound metal stylus may be made in other ways, as for instance by first forming a bar or rod of the low heat-conductive metal to be used for the core, centering it in a mold and spacing it from the walls thereof, and casting around such bar or rod the metal of high heat-conductivity, using of course the -usual precautions. for preventing oxidation. The metal body thus made is allowed to cool to a workable ltemperature and is drawn down to stylus-diameter by means of wire drawing machines, etc.

The stiff and strong metal of the sheath which I employ in the present invention has a number of functions. It gives to the finished product a sleeve or body of convenient size and great mechanical strength which can be threaded and used in a'holding member of a talking machine; and having been co-Worked with the axial or other core of tungsten, it is secured thereto in a way which is impossible with any mechanical fitting or even cementing process. In the working down, the two metals grip each other firmly.

In the use of a needle under this invention the sheath of stiff and strong and hard metal does not come into operative contact `with the record since it is removed from the finished stylus to a distance above the point of normal engagement of stylus and record. If not so removed the needle would of course be subject to the objections of a needle of steel or the like. While the sheath metal is not soft, yet it is not as hard as the tungsten andif allowed to come into engagement with the record it would wear away enough to give uneven surfaces; z'. c., to produce the objectionable qualities of the ordinary needle.

With a tungsten cored and pointed needle under the present invention having the stiff and strong metal removed to a point above the point of engagement, smooth and good reproduction of the sound can be obtained and wear of a kind which will causescratching and discordant sounds does not occur. The needle may be used in reproducing some hundreds of records or until it has worn 'out of shape.

While in the present invention the core and sheath are co-worked togetherand the core of tungsten or like metal extends back into the sheath metal a substantial distance and is in (-o-worked engagement therewith, it is not necessary to have it extend the full length when used in a talking machine. For example, stjjli with exposed tungsten points produced iu the described way need not be cut the full length of the stylus used in a talking machine holding member, but may be, for example, one-half that length, the wire being cut in half lengths. To this half length needle may be butt-welded a continuation or shank of steel or the like.

Instead oftungsten or tungsten alloys, molybdenum, titanium and various other very hard metals may be employed. I regard tungsten or its alloys however as the best for the present purposes. An article produced by cementing tungsten grains into an integral whole may also be used.

While I have specifically mentioned tung* sten and its alloys as the core to be used and steel or nickel-steel as the sheath, it is to be understood that they are mentioned as typical examples of Athe invention. In its broader aspects this invention contemplates the use of a hard core of any metal having an envelop of stiff yand strong metal. Usually the core isa metal having the characteristics of tungsten, thatis, a tendency to become fibrous afterA being heated, and the sheath is advantageously an easilyworkable metal, but stiff and strong enough to support the coreand at the saine time not subcore above pointed out.

Lecce-ia In the described process the tungsten core is worked hot or at practically uniform temperature with the aid of the heat retaining steel or nickel envelop with great advantage to its texture. It is not exposed to sudden surface chillings, as is the case with tungsten .worked naked. .As explained, local temperature differences in tungsten tend to equalize quite slowly. The core metal in the present invention has a fine-grained non- `librous texture diliicult, if not impossible, to zittain by other methods in material of as small diameter as here contemplated. And the use of the envelop has the further advantage that when it is removed, a core of the right dimensions for stylus purposes may be directly produced without cutting or grinding. l

In the manufacture, the two metals are assembled in a predetermined ratio or proportions and worked Cdown hot at a suitable temperature till a cored wire is produced of suitable dimensions for making Styli. After the cored wire is produced it may or ma not .be reduced somewhat further in the sty us making operation. Ordinarily I make the nal stylus with its core of dimensich for contacting with the record grooves now generally in use; say, about 0.006 inch in diameter. The length of exposed core is generally Jfrom 0.01 to 0.015 inch. Y

The accompanying drawing shows successively the steps of manufacturing the stylus in accordance with one embodiment of my invention.

In the drawing, Figure 1 is a longitudinal sectionshowing two metals assembled.

Fig. 2 is asimilar view after the .metals have been heated and united.

Fig. 3 is a longitudinal section onfan enlarged scale showing the compound metal bar 'after it has been drawn or swaged.

Fig. 4 is an elevation of the complete stylus on an enlarged scale. 5

The bar or core 1 of low heat conductive and low expansion metal such yas tungsten is first produced and is then inserted in a hot tube 2 of fmetal ofhigher heat conductivity such as nickel, steel or nickel-steel and the two are then heated to such a temperature that unequal expansion causes a workable holding union between them as is seen in Fig. 2. The compound metal bar thus produced is then reduced in cross sectional area by swagingor drawing until it is of stylus diameter as shown in Fig. 3; this figurebeing. on an enlarged scale. The drawn wire 1s then cut into stylus lengths and the sheath or. envelop is then turned off or otherwise removed from one or both ends to expose suicient length of the core to travel in the record grooves. Usually it is not K necessary to ppint the ends butl they may be pomted 1f desired. In Fig. 4 I have shown on an enlarged scale a complete stylus hav ing the core projecting on both ends, one end being pointed.

`What I claim is 1. The process of making talking machine styli which comprises enveloping a hard metal core of low heat conductivity and low expansion with a metal'of higher heat conductivity, drawing the compound article so produced down to stylus diameter, cutting the same into stylus lengths, and exposing the core at one end of each such length.

2. rIhe process of making talking machine styli which comprises enveloping a tungsten group metal core with a metal of higher heat conductivity and higher expansion, drawing the compound article so produced down to stylus diameter, cutting the same into stylus lengths, and exposing the lcore at one end of each such length.

3. The process of making talking machine styli which comprises enveloping a tungsten corewith a metal of higher heat conductivity and higher expansion, drawing the com pound artlcle so produced down to stylus diameter, cutting the same into stylus lengths, and exposing the core at one end of each such length.

4. The process of making talking machine styli which comprises enveloping a hard metal of low heat conductivity and low expansion with a ferrous metal, drawing the compound article so produced down to stylus diameter, cutting the same into stylus lengths, and exposing the core at one end .of

each such length.

5. The process of making talking machine styli which comprises enveloping a hard metal of low heat conductivity and low exp'ansion with nickel steel, drawing the compound article so produced down to stylus diameter, cutting the same into stylus lenvths, and exposing the core at one end of each such length.

6. The process of making talking machine st li which comprisesl enveloping tungsten with a ferrous metal, drawing the compound article so produced down to stylus diameter, cutting the same into stylus lengths, and exposing the core at one end of each such length.

' 7. The process of making talking machine vstyli which comprises enveloping tungsten of hard metal of low heat conductivity and expansion and a sheath of stiff and strong metal of high heat .conductivity and expansion, gripping said core.

10. A compound metal stylus comprising an exposed core of tungsten group metal and la'sheath of metal of high conductivity and Aexpansion gipping sald core.

11. A compound metal stylus comprising an exposed core of tungsten and a sheath of metal of high conductivity and' expansion gripping said core.

12. A compound metal stylus comprising an exposed core of tungsten group metal and a sheath of nickel steel gripping said core.

13. A compound metal stylus comprising an exposed core of tungsten and a sheath of nickel steel gripping said core.

14. A compound metal stylus comprising an exposed core of non-fibrous metal and a supporting sheath of stiff' and strong metal of the ferrous group gripping said core.

15. A phonograph needle Vcomprising a metal Sheath filled With a wire, the two having a drawn union with each other, one end of the Wire being exposed for a short distance to form .the record engagngpoint. e

'16. 'A phonograph needle comprising a meta-1 sheath filled with a wire, the two having a. dra-wn union with each other, said nedle having a record engaging point at its en In testimony whereof, I aiiix my signature in the presence of two subscribing witnesses.

'BY RON E. ELDRED.

Witnesses:

GEO. F. Lm'rmer1 W. S. HOWELL. 

